The present invention relates to modular conveyor belts and chains, and more particularly to an active control roller top conveyor module and a modular conveying assembly including at least one of the conveyor modules.
Modular belting and chains are formed from interconnected modules that are supported by a frame and driven to transport a product. Each module has a support surface which supports the product as the belting or chain is being driven along the frame. Adjacent modules are connected to each other by hinge pins inserted through hinge members extending from adjacent modules in the direction of the belt travel.
Modular belts can transport products in the direction of conveyor travel, but have difficulty accumulating a product to reduce backline pressure. In addition, the belt can easily damage high friction products during accumulation. One known solution to this problem is to rotatably mount rollers directly on the hinge pin connecting modules together, such that the hinge pin supports the rollers between hinge members. The roller rotates about an axis of rotation that is substantially coaxial with the hinge pin axis. Because it is necessary to have a portion of the roller extend above the module to engage the object being conveyed to reduce backline pressure, the required roller diameter is determined by the hinge pin location and the height of the module. Unfortunately, this often results in requiring a large diameter roller that extends both above and below the module when that configuration is not always desired. Moreover, supporting the roller on the pin alone can result in undesirable pin wear.
Another known solution for reducing backline pressure is disclosed in U.S. Pat. No. 4,231,469 issued to Arscott. In Arscott, rollers are supported by roller cradles between modules. The rollers extend above the cradle for rolling contact with an object being conveyed independent of the location of the hinge pins. The rollers reduce friction between the belt and the object. Unfortunately, assembling the roller in the cradle is difficult, requiring insertion of the roller into the cradle, and then slipping an axle or two stub axles through holes formed through the cradle walls and into the roller. The axle must then be secured to prevent it from slipping out of one of the holes formed in the cradle wall.
Rexnord Industries, LLC of Milwaukee, Wis. developed roller top conveying modules that include roller axle supports that support freewheeling rollers above a module top surface. See U.S. Pat. Nos. 8,151,978, 5,096,050, 4,880,107, and 4,821,169. These modules are easily assembled and do not require oversize rollers extending through the conveyor modules. These prior art modules allow accumulation of product being conveyed by a conveying system formed from modules by providing a low backline pressure when the products are stopped on the moving modules. Absent individual external stops for each product being conveyed, the conveyed products engage other products when accumulating on the conveyor system.